What is the molarity of a solution made by mixing 2.80 g of koh with enough water make 750 ml of solution?
1 answer:
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<u>Answer:</u> The enthalpy change of the reaction is -361.6 kJ
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
Moles of sodium = 0.025 moles
Molar mass of sodium = 23 g/mol
Putting values in above equation, we get:
We are given:
Mass of water = 100.00 g
Mass of sodium = 0.575 g
Mass of solution = 100.00 + 0.575 = 100.575 g
To calculate the amount of heat absorbed, we use the equation:
where,
q = amount of heat absorbed = ?
m = mass of solution = 100.575 g
C = specific heat capacity of solution = 4.18 J/g°C
= change in temperature =
Putting all the values in above equation, we get:
When heat is absorbed by the solution, this means that heat is getting released by the reaction.
<u>Sign convention of heat:</u>
When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.
For the given chemical reaction:
When 0.025 moles of sodium is reacted, the heat released by the reaction is 4.52 kJ
So, when 2 moles of sodium will react, the heat released by the reaction will be =
Hence, the enthalpy change of the reaction is -361.6 kJ